diff options
Diffstat (limited to 'compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs')
| -rw-r--r-- | compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs b/compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs new file mode 100644 index 000000000..6c10baa53 --- /dev/null +++ b/compiler/rustc_codegen_cranelift/src/abi/pass_mode.rs @@ -0,0 +1,299 @@ +//! Argument passing + +use crate::prelude::*; +use crate::value_and_place::assert_assignable; + +use cranelift_codegen::ir::{ArgumentExtension, ArgumentPurpose}; +use rustc_target::abi::call::{ + ArgAbi, ArgAttributes, ArgExtension as RustcArgExtension, CastTarget, PassMode, Reg, RegKind, +}; +use smallvec::{smallvec, SmallVec}; + +pub(super) trait ArgAbiExt<'tcx> { + fn get_abi_param(&self, tcx: TyCtxt<'tcx>) -> SmallVec<[AbiParam; 2]>; + fn get_abi_return(&self, tcx: TyCtxt<'tcx>) -> (Option<AbiParam>, Vec<AbiParam>); +} + +fn reg_to_abi_param(reg: Reg) -> AbiParam { + let clif_ty = match (reg.kind, reg.size.bytes()) { + (RegKind::Integer, 1) => types::I8, + (RegKind::Integer, 2) => types::I16, + (RegKind::Integer, 3..=4) => types::I32, + (RegKind::Integer, 5..=8) => types::I64, + (RegKind::Integer, 9..=16) => types::I128, + (RegKind::Float, 4) => types::F32, + (RegKind::Float, 8) => types::F64, + (RegKind::Vector, size) => types::I8.by(u16::try_from(size).unwrap()).unwrap(), + _ => unreachable!("{:?}", reg), + }; + AbiParam::new(clif_ty) +} + +fn apply_arg_attrs_to_abi_param(mut param: AbiParam, arg_attrs: ArgAttributes) -> AbiParam { + match arg_attrs.arg_ext { + RustcArgExtension::None => {} + RustcArgExtension::Zext => param.extension = ArgumentExtension::Uext, + RustcArgExtension::Sext => param.extension = ArgumentExtension::Sext, + } + param +} + +fn cast_target_to_abi_params(cast: CastTarget) -> SmallVec<[AbiParam; 2]> { + let (rest_count, rem_bytes) = if cast.rest.unit.size.bytes() == 0 { + (0, 0) + } else { + ( + cast.rest.total.bytes() / cast.rest.unit.size.bytes(), + cast.rest.total.bytes() % cast.rest.unit.size.bytes(), + ) + }; + + // Note: Unlike the LLVM equivalent of this code we don't have separate branches for when there + // is no prefix as a single unit, an array and a heterogeneous struct are not represented using + // different types in Cranelift IR. Instead a single array of primitive types is used. + + // Create list of fields in the main structure + let mut args = cast + .prefix + .iter() + .flatten() + .map(|®| reg_to_abi_param(reg)) + .chain((0..rest_count).map(|_| reg_to_abi_param(cast.rest.unit))) + .collect::<SmallVec<_>>(); + + // Append final integer + if rem_bytes != 0 { + // Only integers can be really split further. + assert_eq!(cast.rest.unit.kind, RegKind::Integer); + args.push(reg_to_abi_param(Reg { + kind: RegKind::Integer, + size: Size::from_bytes(rem_bytes), + })); + } + + args +} + +impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> { + fn get_abi_param(&self, tcx: TyCtxt<'tcx>) -> SmallVec<[AbiParam; 2]> { + match self.mode { + PassMode::Ignore => smallvec![], + PassMode::Direct(attrs) => match self.layout.abi { + Abi::Scalar(scalar) => smallvec![apply_arg_attrs_to_abi_param( + AbiParam::new(scalar_to_clif_type(tcx, scalar)), + attrs + )], + Abi::Vector { .. } => { + let vector_ty = crate::intrinsics::clif_vector_type(tcx, self.layout).unwrap(); + smallvec![AbiParam::new(vector_ty)] + } + _ => unreachable!("{:?}", self.layout.abi), + }, + PassMode::Pair(attrs_a, attrs_b) => match self.layout.abi { + Abi::ScalarPair(a, b) => { + let a = scalar_to_clif_type(tcx, a); + let b = scalar_to_clif_type(tcx, b); + smallvec![ + apply_arg_attrs_to_abi_param(AbiParam::new(a), attrs_a), + apply_arg_attrs_to_abi_param(AbiParam::new(b), attrs_b), + ] + } + _ => unreachable!("{:?}", self.layout.abi), + }, + PassMode::Cast(cast) => cast_target_to_abi_params(cast), + PassMode::Indirect { attrs, extra_attrs: None, on_stack } => { + if on_stack { + // Abi requires aligning struct size to pointer size + let size = self.layout.size.align_to(tcx.data_layout.pointer_align.abi); + let size = u32::try_from(size.bytes()).unwrap(); + smallvec![apply_arg_attrs_to_abi_param( + AbiParam::special(pointer_ty(tcx), ArgumentPurpose::StructArgument(size),), + attrs + )] + } else { + smallvec![apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs)] + } + } + PassMode::Indirect { attrs, extra_attrs: Some(extra_attrs), on_stack } => { + assert!(!on_stack); + smallvec![ + apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs), + apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), extra_attrs), + ] + } + } + } + + fn get_abi_return(&self, tcx: TyCtxt<'tcx>) -> (Option<AbiParam>, Vec<AbiParam>) { + match self.mode { + PassMode::Ignore => (None, vec![]), + PassMode::Direct(_) => match self.layout.abi { + Abi::Scalar(scalar) => { + (None, vec![AbiParam::new(scalar_to_clif_type(tcx, scalar))]) + } + Abi::Vector { .. } => { + let vector_ty = crate::intrinsics::clif_vector_type(tcx, self.layout).unwrap(); + (None, vec![AbiParam::new(vector_ty)]) + } + _ => unreachable!("{:?}", self.layout.abi), + }, + PassMode::Pair(_, _) => match self.layout.abi { + Abi::ScalarPair(a, b) => { + let a = scalar_to_clif_type(tcx, a); + let b = scalar_to_clif_type(tcx, b); + (None, vec![AbiParam::new(a), AbiParam::new(b)]) + } + _ => unreachable!("{:?}", self.layout.abi), + }, + PassMode::Cast(cast) => (None, cast_target_to_abi_params(cast).into_iter().collect()), + PassMode::Indirect { attrs: _, extra_attrs: None, on_stack } => { + assert!(!on_stack); + (Some(AbiParam::special(pointer_ty(tcx), ArgumentPurpose::StructReturn)), vec![]) + } + PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => { + unreachable!("unsized return value") + } + } + } +} + +pub(super) fn to_casted_value<'tcx>( + fx: &mut FunctionCx<'_, '_, 'tcx>, + arg: CValue<'tcx>, + cast: CastTarget, +) -> SmallVec<[Value; 2]> { + let (ptr, meta) = arg.force_stack(fx); + assert!(meta.is_none()); + let mut offset = 0; + cast_target_to_abi_params(cast) + .into_iter() + .map(|param| { + let val = ptr.offset_i64(fx, offset).load(fx, param.value_type, MemFlags::new()); + offset += i64::from(param.value_type.bytes()); + val + }) + .collect() +} + +pub(super) fn from_casted_value<'tcx>( + fx: &mut FunctionCx<'_, '_, 'tcx>, + block_params: &[Value], + layout: TyAndLayout<'tcx>, + cast: CastTarget, +) -> CValue<'tcx> { + let abi_params = cast_target_to_abi_params(cast); + let abi_param_size: u32 = abi_params.iter().map(|param| param.value_type.bytes()).sum(); + let layout_size = u32::try_from(layout.size.bytes()).unwrap(); + let stack_slot = fx.bcx.create_stack_slot(StackSlotData { + kind: StackSlotKind::ExplicitSlot, + // FIXME Don't force the size to a multiple of 16 bytes once Cranelift gets a way to + // specify stack slot alignment. + // Stack slot size may be bigger for for example `[u8; 3]` which is packed into an `i32`. + // It may also be smaller for example when the type is a wrapper around an integer with a + // larger alignment than the integer. + size: (std::cmp::max(abi_param_size, layout_size) + 15) / 16 * 16, + }); + let ptr = Pointer::new(fx.bcx.ins().stack_addr(pointer_ty(fx.tcx), stack_slot, 0)); + let mut offset = 0; + let mut block_params_iter = block_params.iter().copied(); + for param in abi_params { + let val = ptr.offset_i64(fx, offset).store( + fx, + block_params_iter.next().unwrap(), + MemFlags::new(), + ); + offset += i64::from(param.value_type.bytes()); + val + } + assert_eq!(block_params_iter.next(), None, "Leftover block param"); + CValue::by_ref(ptr, layout) +} + +/// Get a set of values to be passed as function arguments. +pub(super) fn adjust_arg_for_abi<'tcx>( + fx: &mut FunctionCx<'_, '_, 'tcx>, + arg: CValue<'tcx>, + arg_abi: &ArgAbi<'tcx, Ty<'tcx>>, + is_owned: bool, +) -> SmallVec<[Value; 2]> { + assert_assignable(fx, arg.layout().ty, arg_abi.layout.ty, 16); + match arg_abi.mode { + PassMode::Ignore => smallvec![], + PassMode::Direct(_) => smallvec![arg.load_scalar(fx)], + PassMode::Pair(_, _) => { + let (a, b) = arg.load_scalar_pair(fx); + smallvec![a, b] + } + PassMode::Cast(cast) => to_casted_value(fx, arg, cast), + PassMode::Indirect { .. } => { + if is_owned { + match arg.force_stack(fx) { + (ptr, None) => smallvec![ptr.get_addr(fx)], + (ptr, Some(meta)) => smallvec![ptr.get_addr(fx), meta], + } + } else { + // Ownership of the value at the backing storage for an argument is passed to the + // callee per the ABI, so we must make a copy of the argument unless the argument + // local is moved. + let place = CPlace::new_stack_slot(fx, arg.layout()); + place.write_cvalue(fx, arg); + smallvec![place.to_ptr().get_addr(fx)] + } + } + } +} + +/// Create a [`CValue`] containing the value of a function parameter adding clif function parameters +/// as necessary. +pub(super) fn cvalue_for_param<'tcx>( + fx: &mut FunctionCx<'_, '_, 'tcx>, + local: Option<mir::Local>, + local_field: Option<usize>, + arg_abi: &ArgAbi<'tcx, Ty<'tcx>>, + block_params_iter: &mut impl Iterator<Item = Value>, +) -> Option<CValue<'tcx>> { + let block_params = arg_abi + .get_abi_param(fx.tcx) + .into_iter() + .map(|abi_param| { + let block_param = block_params_iter.next().unwrap(); + assert_eq!(fx.bcx.func.dfg.value_type(block_param), abi_param.value_type); + block_param + }) + .collect::<SmallVec<[_; 2]>>(); + + crate::abi::comments::add_arg_comment( + fx, + "arg", + local, + local_field, + &block_params, + arg_abi.mode, + arg_abi.layout, + ); + + match arg_abi.mode { + PassMode::Ignore => None, + PassMode::Direct(_) => { + assert_eq!(block_params.len(), 1, "{:?}", block_params); + Some(CValue::by_val(block_params[0], arg_abi.layout)) + } + PassMode::Pair(_, _) => { + assert_eq!(block_params.len(), 2, "{:?}", block_params); + Some(CValue::by_val_pair(block_params[0], block_params[1], arg_abi.layout)) + } + PassMode::Cast(cast) => Some(from_casted_value(fx, &block_params, arg_abi.layout, cast)), + PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => { + assert_eq!(block_params.len(), 1, "{:?}", block_params); + Some(CValue::by_ref(Pointer::new(block_params[0]), arg_abi.layout)) + } + PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => { + assert_eq!(block_params.len(), 2, "{:?}", block_params); + Some(CValue::by_ref_unsized( + Pointer::new(block_params[0]), + block_params[1], + arg_abi.layout, + )) + } + } +} |